Interbody standalone intervertebral implant

ABSTRACT

Stand-alone interbody fusion devices and corpectomy devices suitable for use with an oblique implantation. The stand-alone interbody fusion devices may include a spacer having a substantially U-shaped body and a plate coupled to the spacer. The overall shape of the implant is asymmetrical such that a median plane, an oblique plane, or both planes divide the spacer and the plate into two asymmetrical halves. The implants are shaped and configured to allow for an oblique or anterolateral approach to the spine or an oblique corpectomy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/412,473 filed on May 15, 2019 which is a continuation of U.S. patentapplication Ser. No. 14/190,967, filed on Feb. 26, 2014, which claimspriority to provisional application No. 61/789,673 filed Mar. 15, 2013.This application also cross-references U.S. Pat. No. 8,328,872, whichissued Dec. 11, 2012. The entire contents of both documents areincorporated herein by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The present disclosure generally relates to fixation devices forpositioning and immobilizing adjacent vertebral bodies and corpectomydevices. In particular, the devices may include stand-alone interbodyfusion and oblique corpectomy devices containing at least one spacer andat least one plate.

BACKGROUND OF THE INVENTION

As people age, the intervertebral discs in the spinal column may startto deteriorate. Subsequently, the intervertebral discs being to loseheight. As a result of the loss of height between vertebral bodies, thenerves exiting from the spinal canal become compressed and pinched,which causes pain among other neurological deficits. One solution is toinsert a spacer in place of the disc to restore the height and topromote fusion between adjacent vertebral bodies to permanently maintainthe height restoration. Additional fixation is also needed to stabilizethe spinal segment. A plate is usually provided, the plate beingpositioned on the anterior portions of the adjacent vertebral bodies. Insome cases, the profile of the plate becomes obstructive to the anatomy.The approach to the spine is also significant in that a direct anteriorapproach requires navigation or dissection of vascular anatomy. As aresult, there is a need to incorporate the plate and the spacer into onedevice, to limit any profile protruding out of the spine column, and toavoid proximal anatomy from a direct anterior approach. With regard tocorpectomy devices, there is a similar need for access to perform thecorpectomy and suitable devices to replace at least a portion of damagedor collapsed vertebrae.

SUMMARY OF THE INVENTION

To meet this and other needs, stand-alone interbody fusion implants andcorpectomy implants suitable for an oblique or anterolateral approach tothe spine or for use with an oblique corpectomy are provided. The shapeand configuration of the implants are particularly suitable for anoblique or anterolateral approach to the spine due to the asymmetricalnature of the implant design. The multi-component spacer and plate arealso contained within the disc space to provide for a low or zeroprofile with respect to the anterior and lateral aspects of the spinalcolumn. Thus, the plate and spacer are incorporated into a single deviceand any profile protruding out of the spinal column is limited.

According to one embodiment, an intervertebral implant for implantationin an intervertebral space between adjacent vertebrae includes a spacerand a plate. The spacer has a substantially U-shaped body, a superiorsurface, an inferior surface, a first end, and a second end. Theinferior and superior surfaces each have a contact area configured toengage adjacent vertebrae. The plate has an upper surface, a lowersurface, a first end, a second end, an anterior surface, and at leastone hole traversing the plate for receiving a fastener (e.g., a screw).The plate is coupled to the spacer where the first end of the spacerengages the first end of the plate and the second end of the spacerengages the second end of the plate. The implant is asymmetrical suchthat a median plane divides the spacer and the plate into twoasymmetrical halves. In addition or in the alternative, the implant maybe asymmetrical such that an oblique plane divides the spacer and theplate into two asymmetrical halves.

The asymmetrical nature of the implant may allow for an oblique oranterolateral approach to the spine (e.g., lumbar, cervical). Inparticular, the implant may be inserted in an oblique direction, e.g.,at an angle of about 45° with respect to the mid-sagittal plane. Byproviding this oblique or anterolateral approach, no dissection of thevessels in front of the vertebrae is required. Thus, the vascularanatomy of the patient may be avoided. In addition, when fully inserted,the implant may be contained within the disc space to provide for a lowor zero profile design in regard to the anterior and lateral aspects ofthe spinal column.

The implant may be asymmetrical in a number of different ways. Thespacer has a substantially U-shaped body, which may be asymmetricalalong the median plane, the oblique plane, or both planes. The plate mayhave a curved body, which also may be asymmetrical along the medianplane, the oblique plane, or both planes. Thus, the plate, the spacer,or both of the plate and the spacer may be independently asymmetrical.The plate may be asymmetrical along the oblique plane where the firstend of the plate extends a distance beyond the second end of the plateor vice versa. Similarly, the spacer may be asymmetrical along theoblique plane where the second end of the spacer extends a distancebeyond the first end of the spacer or vice versa. The spacer may furtherinclude a leading taper. The leading taper may be located along theinsertion direction of the implant, which in the case of an obliquedirection may allow for the leading taper to be positionedasymmetrically on the spacer. For example, the leading taper may beasymmetrically positioned such that the leading taper crosses orintersects the oblique plane.

The spacer and the plate may be coupled or connected together in anysuitable manner. In one embodiment, the first and second ends of theplate and the first and second ends of the spacer each comprise firstand second projections with a recess defined therebetween. The firstprojections of the spacer may include a sloped upper surface whichcorresponds to a sloped lower surface of the first projections of theplate. At least one of the first and second projections of the plate orthe spacer is matingly received in the corresponding recess of the plateor the spacer. For example, the second projections of the plate may bedovetailed or friction fit within the recesses of the spacer. Inaddition or in the alternative, the spacer and the plate may be securedtogether with pins.

The plate of the implant may include one or more bores or through holesdesigned to accommodate fixation devices or fasteners, such as screws.The anterior surface may include one or more eyebrows projecting pastthe upper or lower surfaces which accommodate the locations of thethrough holes. The holes for receiving fasteners, such as screws maytraverse the anterior surface of the plate at an angle divergent to ahorizontal plane in order to secure the implant to one or both of theadjacent vertebrae. The implant may also include a locking mechanismdisposed on the plate for preventing back out of the screws. Forexample, a cam-style blocking mechanism may be used with screws thatcapture the fixation device screws once they are inserted fully into theplate.

Unlike traditional spacers, which may contain one or more graftretaining areas where the spacer completely surrounds or envelops thegraft retaining area, the spacer is substantially U-shaped with an openportion. When the spacer and plate are coupled together, the spacer andthe plate together define an open graft area. In other words, theperimeter of the U-shaped spacer and the perimeter of the plate definean open area. The open graft area may extend from the superior surfaceto the inferior surface of the spacer. The opening may be configured forreceiving bone graft material to promote fusion of the adjacentvertebral bodies. The spacer may also include a plurality of protrusionson the contact areas of the superior and inferior surfaces for engagingthe adjacent vertebrae.

The plate and the spacer may be formed from any suitable biocompatiblematerials. For example, the plate may be manufactured from abiocompatible metal, such as titanium, for example. The spacer also maybe manufactured from any suitable material, such as a biocompatibleplastic, like polyether ether ketone (PEEK), for example.

According to another embodiment, a multi-level corpectomy implant forimplantation in at least a portion of at least one vertebrae and in anintervertebral space between adjacent vertebrae includes a spacer. Thespacer has a superior surface, an inferior surface, a first lateralsurface, a second lateral surface, a front surface, and a rear surface.The first and second lateral surfaces each have at least one contactarea configured to engage a portion of the vertebrae exposed by acorpectomy. The spacer is also configured to extend between at least twoadjacent vertebrae. The spacer is shaped and configured to allow for anoblique or anterolateral approach.

The spacer may include at least one attachment mechanism to secure thespacer to the portion of the vertebrae exposed by the corpectomy. Forexample, the attachment mechanism may include one or more fasteners,screws, pins, or the like. In addition or in the alternative, theattachment mechanism may include a plurality of protrusions on thecontact areas of the first and second lateral surfaces for engaging theportion of the vertebrae exposed by the corpectomy.

The multi-level corpectomy implant may also include one or more plates.The plate may be coupled to a portion of the front surface of thespacer. The plate has an anterior surface and at least one holetraversing through the anterior surface for receiving a fastener, suchas a screw to secure the plate to one of the adjacent vertebrae. Theimplant may include two plates: a first plate coupled to a first portionof the front surface of the spacer and a second plate coupled to asecond portion of the front surface of the spacer. The first plate maysecure the spacer to a first vertebral body and the second plate maysecure the spacer to a second vertebral body adjacent to the firstvertebral body, for example, using one or more screws.

The plate and spacer may be comprised of any suitable material. Forexample, the spacer may be formed from a flexible elastomer. The spacermay also include a multi-component body including a biocompatibleplastic and a flexible elastomer. The spacer may include amulti-component body including a first cage made from a biocompatibleplastic (e.g., PEEK), a second cage comprising a biocompatible plastic(e.g., PEEK), and a flexible elastomer sandwiched between the first andsecond cages. The first and second lateral surfaces of the first cageand the second cage may each have the contact area configured to engagethe portion of the vertebrae exposed by the corpectomy. In addition, thefirst and second cages may each define an open graft area extending fromthe first lateral surface to the second lateral surface suitable forreceiving bone graft material.

BRIEF DESCRIPTION OF DRAWING

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawing. It is emphasizedthat, according to common practice, the various features of the drawingare not to scale. On the contrary, the dimensions of the variousfeatures are arbitrarily expanded or reduced for clarity. Included inthe drawing are the following figures:

FIG. 1 is an exploded view of one embodiment of an intervertebralimplant including a spacer and a plate;

FIG. 2 is a top view of the intervertebral implant depicted in FIG. 1once assembled;

FIG. 3 is a side view of the intervertebral implant provided in FIG. 2;

FIG. 4 is an alternative side view of the intervertebral implantdepicted in FIG. 3;

FIG. 5 is an anterior view of a portion of lumbar spine with theintervertebral implant depicted in FIG. 4 implanted between adjacentvertebrae;

FIG. 6 is a top view of the portion of the spine depicted in FIG. 5 withthe intervertebral implant depicted in FIG. 4 implanted between adjacentvertebrae;

FIG. 7 depicts a top view of the intervertebral implant depicted in FIG.4;

FIG. 8 provides a front view of the intervertebral implant depicted inFIG. 4;

FIG. 9 is a top view of a portion of the cervical spine of anotherembodiment with an oblique corpectomy implant including a spacer and aplate; and

FIG. 10 is a perspective view of a portion of the cervical spine and twoalternative spacers suitable for use with an oblique corpectomy.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the disclosure are generally directed to stand-aloneinterbody fusion implants and corpectomy implants suitable for use withoblique implantation. Specifically, the implants are designed to allowfor an oblique or anterolateral approach to the spine, including thelumbar and cervical spine. In particular, the implants may be insertedin an oblique direction, e.g., at an angle of about 45° with respect tothe mid-sagittal plane. By providing this oblique or anterolateralapproach, no dissection of the vessels in front of the vertebrae isrequired and contact with the vascular anatomy of the patient can beavoided or minimized.

Certain embodiments may be used on the cervical, thoracic, lumbar,and/or sacral segments of the spine. For example, the size and massincrease of the vertebrae in the spine from the cervical to the lumbarportions is directly related to an increased capacity for supportinglarger loads. This increase in load bearing capacity, however, isparalleled by a decrease in flexibility and an increase insusceptibility to strain. When rigid immobilization systems are used inthe lumbar segment, the flexibility is decreased even further beyond thenatural motion restriction of that segment. Replacing the conventionalrigid immobilization systems with certain embodiments disclosed hereinmay generally restore a more natural movement and provide added supportto the strain-susceptible areas.

As used herein and in the claims, the terms “comprising” and “including”are inclusive or open-ended and do not exclude additional unrecitedelements, compositional components, or method steps. Accordingly, theterms “comprising” and “including” encompass the more restrictive terms“consisting essentially of” and “consisting of.”

FIGS. 1-8 illustrate different views of one particular embodiment of thestand-alone intervertebral implant 10. As shown in the exploded view ofFIG. 1, the implant 10 includes a spacer 12 and a plate 14. The spacer12 includes a superior surface 42 and an inferior surface 44. Thesuperior and inferior surfaces 42, 44 each have a contact area 22configured to contact and engage adjacent vertebrae 80. The spacer 12has a curved or substantially U-shaped body with a first end 46 and asecond end 48. The plate 14 has an upper surface 62, a lower surface 64,an anterior surface 65, a first end 66, a second end 68, and at leastone bore or screw hole 18 traversing the plate 14 for receiving a screw30. The plate 14 is affixed to the spacer 12. In particular, the plate14 is coupled to the spacer 12 where the first end 46 of the spacer 12engages or joins the first end 66 of the plate 14 and the second end 48of the spacer 12 engages or joins the second end 68 of the plate 14.

As is evident in FIG. 2, the implant 10 is asymmetrical such that amedian plane M divides the spacer 12 and the plate 14 into twoasymmetrical halves. In addition or in the alternative, the implant 10may be asymmetrical such that an oblique plane O divides the spacer 12and the plate 14 into two asymmetrical halves. As used herein,asymmetrical is intended to encompass an implant 10 lacking symmetryfrom side-to-side along either or both the median plane M and theoblique plane O when viewed from a top elevation, for example, asprovided in FIG. 2. In other words, the median plane M and/or theoblique plane O bisect the implant 10 into two parts that are notidentical or mirror images of one another.

The asymmetrical nature of the implant 10 may allow for an oblique oranterolateral approach to the spine (e.g., lumbar, cervical). Inparticular, the implant 10 may be inserted in an oblique direction alongthe oblique plane O. As shown in FIGS. 2 and 6, the oblique plane O maybe at an angle A relative to the mid-sagittal plane S (e.g., the same asthe median plane M). The angle A may be an angle of about 45° withrespect to the mid-sagittal plane S and/or the median plane M. Forexample, the angle A may range from about 10° to about 80°, about 25° toabout 65°, about 35° to about 55°, or about 40° to 50° with respect tothe mid-sagittal plane S and/or the median plane M. This approach by asurgeon can minimize the contact with the vascular anatomy and need todissect vessels in front of the vertebrae, which is necessary with ananterior approach.

The implant 10 may be asymmetrical based on different configurations ofthe plate 14 and the spacer 12. The spacer 12 has a curved, C-shaped, orsubstantially U-shaped body, which may be asymmetrical along the medianplane M, the oblique plane O, or both planes. The plate 14 may also havea curved, C-shaped, or substantially U-shaped body, which also may beasymmetrical along the median plane M, the oblique plane O, or bothplanes. Thus, the plate 14, the spacer 12, or both of the plate 14 andthe spacer 12 may be independently asymmetrical. The shape of the spacer12 and the plate 14 may also be asymmetrical in that the curve is notconsistent. In other words, the curved body for each of the spacer 12and the plate 14 may be skewed from a normal or symmetric curve. Inaddition, the perimeter of the curved body for each of the spacer 12 andthe plate 14 may contain flat or angled segments along the perimeter orperiphery of the implant 10.

As is evident in FIGS. 1 and 2, the plate 14 may be asymmetrical alongthe oblique plane O such that the first end 66 of the plate 14 extends adistance d1 beyond the second end 68 of the plate 14. In other words,the distance d1 is a relative distance between the length of the firstend 66 of the plate 14 less the length of the second end 68 of the plate14. In a corresponding manner, the spacer 12 may be asymmetrical alongthe oblique plane O where the second end 48 of the spacer 12 extends adistance d2 beyond the first end 46 of the spacer 12. Thus, the firstand second ends 66, 68 of the plate 14 are not equivalent or uniform.Again, the distance d2 is a relative distance between the length of thesecond end 48 of the spacer 12 less the length of the first end 46 ofthe spacer 12. The first and second ends 46, 48 of the spacer 12 arealso not equivalent. Although not shown, the distance, length, orconfiguration of the ends or any portion of the plate 14 or the spacer12 may be reversed or modified as would be appreciated by one ofordinary skill in the art to provide an asymmetrical implant 10especially appropriate for insertion and implantation along the obliqueplane O.

The spacer 12 may further include a leading taper 40 for ease ofinsertion. The leading taper 40 may be in the form of a chamfer or abevel which enables self-distraction of the vertebral bodies 80 duringinsertion of the implant 10. The leading taper 40 may be located alongthe insertion direction of the implant 10 (e.g., along the oblique planeO). In the case of an oblique insertion direction, the leading taper 40is positioned asymmetrically on the spacer 12 with respect to the medianplane M. In addition, the leading taper 40 may be asymmetricallypositioned such that the leading taper 40 also crosses or intersects theoblique plane O. As shown in FIG. 2, the leading taper 40 may intersectthe oblique plane O, but the oblique plane O does not necessarily needto bisect the leading taper 40 into equal parts. The leading taper 40may correspond to the angle A, which may range from about 10° to about80°, about 25° to about 65°, about 35° to about 55°, about 40° to 50°,or about 45%, for example.

The spacer 12 and the plate 14 may be coupled, removably coupled,connected, or attached together in any suitable manner known in the art.The spacer 12 and the plate 14 may also be coupled together throughappropriate coupling means or fasteners. Portions of the spacer 12 andthe plate 14 may be assembled together using, alone or in combination, afriction fit, a dovetail assembly, dowel pins, hooks, staples, screws,adhesives, and the like, or any suitable fasteners known in the art,which can be used to permanently attach the spacer 12 and the plate 14together. The implant 10 is in the form of a stand-alone fusion deviceto provide structural stability and a low or zero profile design. Theimplant 10 is preferably assembled before insertion into the disc space.

According to one embodiment shown in FIGS. 3 and 4, the first and secondends 46, 48 of the spacer 12 may be attached to the first and secondends 66, 68 of the plate 14 in the form of a friction fit assembly withor without pins 78 (shown in FIG. 7). For example, the first and secondends 46, 48 of the spacer 12 each comprise first and second projections52, 54 with a recess 56 defined therebetween. The first and second ends66, 68 of the plate 14 also each comprise first and second projections72, 74 with a recess 76 defined therebetween. At least one of the firstand second projections 52, 54 of the spacer 12 or the first and secondprojections 72, 74 of the plate 14 is matingly received in thecorresponding recess 56 of the spacer or the recess 76 of the plate 14.For example, the second projections 74 of the plate 14 may be dovetailedor friction fit within the recesses 56 of the spacer 12 or the secondprojections 54 of the spacer 12 may be dovetailed or friction fit withinthe recesses 76 of the plate 14. The first projections 52 of the spacer12 may be received within the recess 76 of the plate 14 or the firstprojections 72 of the plate 14 may be received within the recess 56 ofthe spacer 12.

In the embodiment shown in FIGS. 1- 4, the second projections 74 of theplate 14 are received within the recesses 56 of the spacer 12 and thefirst projections 52 of the spacer 12 are received with the recesses 76of the plate 14 to couple the spacer 12 and the plate 14 together. Inaddition, the first projections 52 of the spacer 12 may include a slopedupper surface 53. The first projections 72 of the plate 14 may include asloped lower surface 73. The sloped upper surface 53 of the firstprojections 52 of the spacer 12 may therefore correspond and mate withthe sloped lower surface 73 of the first projections 72 of the plate 14to further secure the first end 46 of the spacer 12 to the the first end66 of the plate 14 and the second end 48 of the spacer 12 to the secondend 68 of the plate 14.

In addition or in the alternative, as shown in FIG. 7, the spacer 12 andthe plate 14 may be secured together with pins 78 which traverse atleast a portion of the spacer 12 and/or the plate 14 at a positionproximate to either or both of the first and second ends 46, 48 of thespacer 12 and the first and second end 66, 68 of the plate 14. Thesepins 78 may pass through holes (not shown), for example, in asubstantially perpendicular manner relative to a horizontal plane. Forexample, the pins 78 may be oriented substantially perpendicularrelative to the superior and/or inferior surfaces 42, 44 of the spacer12 and/or the upper and/or lower surfaces 62, 64 of the plate 14. Thepins 78 may pass through the first and second projections of the 52, 54of the spacer 12 and the first and second projections 72, 74 of theplate 14. The pins 78 may be in the form of dowels formed from abiocompatible material, such as titanium, or the pins 78 may be formedfrom tantalum, for example, to enable radiographic visualization.

As depicted in FIG. 5, the intervertebral implant 10 may be implanted inan intervertebral space 86 between adjacent vertebrae 80. In particular,the implant 10 may be implanted in the intervertebral space 86 between afirst superior vertebra 82 and a second inferior vertebra 84. In orderto engage the adjacent vertebrae 80, the spacer 12 may include aplurality of protrusions 13 or teeth on the contact areas 22 of thesuperior and/or inferior surfaces 42, 44. The protrusions 13 on thesuperior and inferior surfaces 42, 44 of each implant 10 grip theendplates of the adjacent vertebrae 80, resist migration, and aid inexpulsion resistance. The plurality of protrusions 13 may be pyramidalin shape, but the protrusions 13 can be configured to be any size orshape to enhance anchoring the spacer 12 and the implant 10 to each ofthe adjacent vertebrae 80.

The implant 10 may also contain an opening 16 configured for receivingbone graft material to promote fusion of the adjacent vertebral bodies80. Unlike a traditional spacer having an opening for receiving graftmaterials where the spacer completely surrounds or envelops the graftretaining area, the spacer 12, as shown in FIG. 1, for example, has acurvature to match the vertebral endplate 80. In particular, the spacer12 has a substantially U-shaped body with a completely open portiondefined between the first and second ends 46, 48. It is only when thespacer 12 and plate 14 are coupled together that the plate 14 closes theopen portion of the spacer 12. It is the combination of the spacer 12and the plate 14 together that defines the inner void or open graft area16. In other words, the perimeter of the U-shaped spacer 12 and theperimeter of the plate 14 together define the inner void or open area16. The open graft area 16 may extend from the superior surface 42 tothe inferior surface 44 of the spacer 12 to define a substantiallyhollow center suitable for retaining one or more bone graft materials.

The intervertebral implant 10 may be positioned in the spine after thedisc portion between the two vertebral bodies 80 is exposed and removed,for example, using rongeurs or other suitable instruments. The posteriorand lateral walls of the annulus are generally preserved to provideperipheral support for the implant 10 and graft materials. A trialdevice attached to a trial holder may then be inserted into the discspace 86 to determine size of the implant 10. This procedure isgenerally conducted using fluoroscopy and tactile feel. The implant 10may be available in various heights and geometric options to fit theanatomical needs of a wide variety of patients. After the appropriatesized implant 10 is selected and attached to an implant holder and drillguide (not shown), the implant 10 may be inserted into the disc space86. Before or after the implant 10 is positioned within the disc space86, supplemental graft material can be used to enhance fusion. Theimplant 10 may be implanted in the vertebral space 86 using an oblique,anterolateral, anterior, posterior, lateral, and/or transforaminalapproach.

The implant 10 is preferably implanted in the vertebral space 86 usingan oblique or anterolateral approach. FIG. 6 depicts a top view of ofthe portion of the lumbar spine including the anterior side 88 and theposterior side 90, with the intervertebral implant 10 implanted betweenadjacent vertebrae 80. As shown, the implant 10 may be placed in thelumbar spine in an oblique direction along the oblique plane O. Theoblique plane O may be at an angle A relative to the mid-sagittal planeS. The angle A may be about 45° with respect to the mid-sagittal planeS. The asymmetrical nature of the implant 10 allows for this oblique oranterolateral approach to the lumbar spine and oblique positioningbetween the adjacent vertebrae 80. Although depicted on the left side inthe quadrant proximate to the anterior side 88 of the vertebra 80, asimilar oblique approach may be taken to position the implant 10 on theright side in the quadrant opposite to the mid-sagittal plane S of thevertebrae 80. When fully inserted, the implant 10 can be fully containedwithin the disc space 86 to provide for a zero-profile in regard to theanterior and lateral aspects of the spinal column. In particular, theimplant 10 does not extend beyond the anterior face 88 or lateral sideof the vertebrae 80.

The implant 10 may be secured to the adjacent vertebrae 80 in anysuitable manner known in the art. The implant 10 may be secured withfasteners, screws, pins, nails, or the like. As shown in FIGS. 3 and 4,the plate 14 of the implant 10 may be secured to the adjacent vertebrae80 using one or more screws 30. The plate 14 includes one or more screwholes 18 to receive the screws 30. The screw holes 18 are configured toreceive the screws 30 at various angles. The screw holes 18 forreceiving the screw 30 may traverse the anterior surface 65 of the plate14 at an angle divergent to a horizontal plane in order to secure theimplant 10 to one or both of the adjacent vertebrae 80. Thus, the screws30 enter the screw holes 18 at specified angles to enter the adjacentvertebrae 80 at the optimal locations. For example, the screws 30 may bealigned so that they anchor into the apophyseal rings of two adjacentvertebral bodies 80.

The anterior surface 65 of the plate 14 may also include one or moreeyebrows 60 projecting past or beyond the upper or lower surfaces 62, 64of the plate 14 providing passage for one or more angled screw holes 18designed to accommodate one or more angles screws 30. As shown in FIG.8, the anterior surface 65 of the plate 14 may include two eyebrows 60extending beyond the upper surface 62 of the plate 14 to accommodate twoangled screw holes 18, which are retaining two angled screws 30configured to secure the implant 10 into the superior vertebra 82. Theplate 14 also includes one eyebrow 60 extending below the lower surface64 of the plate 14 to accommodate one angled screw hole 18, which isretaining a single angled screws configured to secure the implant 10into the inferior vertebra 84. The eyebrows 60 may be rounded and smoothor notched. Although depicted with three screws 30 and with two eyebrows60 extending beyond the upper surface 62 and one eyebrow extendingbeyond the lower surface 64, the eyebrows 60 and positioning of thescrews 30 may be modified to accept any suitable number andconfiguration of screws 30 needed to secure the implant 10 to theadjacent vertebrae 80.

Once the implant 10 is positioned inside the disc space 86, an awl orany similar type of instrument, for example, can be used to drillthrough the screw hole 18 and break the cortex of the adjacent vertebralbody 80. The surgeon performing this procedure may then use a depthgauge to determine the screw length. Once the appropriate screw lengthis determined, screws 30 may be inserted using a self-retainingscrewdriver, for example. Any suitable type of screw 30 may be selectedby one of ordinary skill in the art. For example, the screws 30 mayinclude fixed or variable angle screws of any suitable size withappropriate thread spacing, thread pitch, head design, length, and thelike.

Once inserted, the screws 30 may be secured with an anti-back outprevention or locking mechanism 20. As depicted in FIG. 1, the lockingmechanism 20 may be disposed on the plate 14 (e.g., the anterior surface65) for preventing back out of the screws 30. For example, a cam-styleblocking mechanism may be used with screws 36 that capture the fixationdevice screws 30 once they are inserted fully into the plate 14. One ormore screw holes 28 may be provided on the anterior surface 65 of theplate 14, which at least partially overlap with the screw holes 18. Asshown, the anti-back out mechanism 20 may include two set screws 36 thatretain the screws 18 with the implant 10, although any suitableanti-back out mechanism 20 may be selected by one of ordinary skill inthe art.

The plate 14 and spacer 12 may be comprised of any suitable material.The spacer 12 can be comprised of any material that is conducive to theenhancement of fusion between the two adjacent vertebrae 80. In oneparticular embodiment, the spacer 12 is made of a biocompatible plastic,like polyether ether ketone (PEEK), polyetherketoneketone (PEKK),ultra-high molecular weight (UHMW) polyethylene, or other polymers andplastics known in the art which are physiologically compatible. Anyother materials that are physiologically compatible may also be usedsuch as bone or metal. The plate 14 can also be comprised of anyphysiologically compatible material. In the preferred embodiment, theplate 14 is composed of a biocompatible metal, such as stainless steel,titanium, titanium alloys, surgical steel, and metal alloys, forexample. Preferably, the plate is formed from titanium or a titaniumalloy. Any other materials that are physiologically compatible may alsobe used such as bone or plastic.

According to one embodiment, the multi-part low or zero-profile implant10 is configured to be positioned in between the vertebral bodies 80. APEEK spacer 12 is provided that is configured to be attachable to atitanium plate 14. The PEEK spacer 12 is further provided with acurvature to match the vertebral endplate 80, a leading taper 40 forease of insertion and teeth or protrusions 13 on the superior andinferior surfaces 42, 44 that engage with the endplates of the adjacentvertebral bodies 80 to resist migration. There is also provided athrough hole 16 that extends from the superior surface 42 to theinferior surface 44 of the spacer 12 for receiving bone graft materialto promote fusion of the adjacent vertebral bodies 80.

The titanium plate 14 is provided with bore holes 18 that are configuredto accept fastening devices, such as screws 30 for fixation to thevertebral bodies 80. It should be noted that rather than screws, pins ornail type devices may also be used. The bore holes 18 are aligned sothat they anchor into the apophyseal rings of the two adjacent vertebralbodes 80 for increased fixation. In this particular embodiment, thecam-style blocking mechanism 20 is provided. Specifically, the cam-styleblocking mechanism 20 comprises screws 36 that when turned capture thefixations devices or screws 30 once they are inserted fully into theplate 14. The shape of the implant 10 is configured so that an anterior,oblique, anterolateral, lateral, and/or transforaminal approach may beused in positioning the plate 14 and the spacer 12 in the intervertebralspace 86. When the implant 10 is fully inserted, the implant 10 will becontained within the disc space 86 and will have a zero profile withregard to the anterior and lateral aspects of the spinal column.

According to another embodiment, as illustrated in FIGS. 9 and 10, thereis provided an oblique spacer 112 that may be used as a corpectomydevice. Specifically, a multi-level corpectomy implant 100 includes aspacer 112 for implantation in at least a portion of at least onevertebrae 80 and in an intervertebral space 86 between adjacentvertebrae 80. The spacer 112 includes a superior surface 142, aninferior surface 144, a first lateral surface 150, a second lateralsurface 152, a front surface 146, and a rear surface 148. The first andsecond lateral surfaces 150, 152 each have at least one contact area 122configured to engage a portion 92 of the vertebrae 80 exposed by acorpectomy. The spacer 112 is also configured to extend in theintervertebral space 86 between at least two adjacent vertebrae 80. Thespacer 112 is shaped and configured to allow for an oblique oranterolateral approach (e.g., at an angle of about 45° with respect tothe mid-sagittal plane S).

The spacer 112 may include at least one attachment mechanism to securethe spacer 112 to the portions 92 of the vertebrae 80 exposed by thecorpectomy. FIG. 10 depicts two embodiments for the spacer 112 a, 112 b.For example, the attachment mechanism may include one or more fasteners,screws, pins, or the like. As shown in the spacer 112 a, screws or pins160 on the second lateral surface 152 and/or the first lateral surface150 (not shown) may be provided to secure the spacer 112 a to theportions 92 of the vertebrae 80 exposed by the corpectomy. In additionor in the alternative, as shown in the spacer 112 b, the attachmentmechanism may include a plurality of protrusions 113 on the contactareas 122 of the first and second lateral surfaces 150, 152 for engagingthe portions 92 of the vertebrae 80 exposed by the corpectomy.

The corpectomy implant 100 may further include at least one plate 114.The one or more plates 114 may be coupled to a portion of the frontsurface 146 of the spacer 112. The plate 114 has an anterior surface 165and at least one screw hole 118 traversing through the anterior surface165 for receiving a screw 130 to secure the plate 114 to one of theadjacent vertebrae 80. The plate 114 may be of any suitable size, shape,or configuration as would be recognized by one of ordinary skill in theart. In one embodiment, the implant 100 may include two plates 114: afirst plate 114 coupled to a first portion of the front surface 146 ofthe spacer 112 (e.g., in the region near the superior surface 142proximate to a first vertebra 80) and a second plate 114 coupled to asecond portion of the front surface 146 of the spacer 112 (e.g., in theregion near the inferior surface 144 proximate to the second vertebra80). Thus, the first plate 114 may secure the spacer 112 to a firstvertebral body 80 and the second plate 114 may secure the spacer 112 toa second vertebral body 80, for example, using one or more screws 130.

The plate 114 and the spacer 112 may be comprised of any suitablematerial. FIG. 10 depicts two embodiments for the spacer 112 a, 112 b.For example, the spacer 112 a may be formed from a flexible elastomer.Suitable elastomers may include, for example, polyurethanes, silicones,hydrogels, collagens, hyalurons, cryogels, proteins and other syntheticpolymers that are configured to have a desired range of elastomericmechanical properties, such as a suitable compressive elastic stiffnessand/or elastic modulus. The elastomer is flexible in that it may beslightly flexed or bent, but the elastomer returns to its originalshape.

The spacer 112 b may include a multi-component body including abiocompatible plastic and a flexible elastomer. Biocompatible plasticsmay include polyetheretherketone (PEEK), polyetherketoneketone (PEKK),ultra-high molecular weight (UHMW) polyethylene, or other polymers andplastics known in the art which are biocompatible. The flexibleelastomers include the same elastomers as discussed above. Specifically,the spacer 112 b may include a multi-component body including a firstcage 154 made from a biocompatible plastic (e.g., PEEK), a second cage156 comprising a biocompatible plastic (e.g., PEEK), and a connectorportion 158 comprising a flexible elastomer sandwiched between the firstand second cages 154, 156. The first and second lateral surfaces 150,152 of the first cage 154 and the second cage 156 may each contain thecontact area 122 configured to engage the portions 92 of the vertebrae80 exposed by the corpectomy. In addition, the first and second cages154, 156 may each define an open graft area 116 extending from the firstlateral surface 150 to the second lateral surface 152 suitable forreceiving bone graft material. The implants 100 may be available invarious heights and geometric options to fit the anatomical needs of awide variety of patients.

These implants 10, 100 are specially designed to allow for an oblique oranterolateral approach to the spine (e.g., lumbar, cervical). Inparticular, the implants 10, 100 may be inserted in an oblique directionwith respect to the mid-sagittal plane S. By providing access to thespine with this oblique or anterolateral approach, no dissection of thevessels in front of the vertebrae is required and contact with thevascular anatomy of the patient can be avoided or minimized. The shapeand configuration of the implants 10, 100 are particularly suitable forthe oblique approach based on the asymmetrical nature of the implant 10and the oblique spacer 112 design of the corpectomy implant 100.

Although the invention has been described in detail and with referenceto specific embodiments, it will be apparent to one skilled in the artthat various changes and modifications can be made without departingfrom the spirit and scope of the invention. Thus, it is intended thatthe invention covers the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents. It is expressly intended, for example, that all rangesbroadly recited in this document include within their scope all narrowerranges which fall within the broader ranges. It is also intended thatthe components of the various devices disclosed above may be combined ormodified in any suitable configuration.

We claim:
 1. An intervertebral implant for implantation in anintervertebral space between adjacent vertebrae, the implant comprising:a spacer having a superior surface, an inferior surface, a first end,and a second end, wherein the inferior surface and the superior surfaceseach have a contact area configured to engage adjacent vertebrae; and aplate having an upper surface, a lower surface, a first end, a secondend, and at least one hole traversing the plate for receiving afastener, wherein the plate has an anterior surface comprising at leastone eyebrow projecting past the upper or lower surfaces and configuredto provide passage for at least one angled screw hole; a fastener forextending through the at least one hole; wherein the plate is coupled tothe spacer in an assembled configuration such that the first end of thespacer engages the first end of the plate and the second end of thespacer engages the second end of the plate, wherein the implant isasymmetrical when the spacer is attached to the plate in the assembledconfiguration, wherein the implant is shaped such that no median planedivides the spacer and plate in the assembled configuration into twosymmetrical sections.
 2. The implant of claim 1, wherein the implant isasymmetrical such that an oblique plane divides the spacer and the plateinto two asymmetrical halves.
 3. The implant of claim 2, wherein theplate is asymmetrical along the oblique plane where the first end of theplate extends a distance beyond the second end of the plate.
 4. Theimplant of claim 2, wherein the spacer is asymmetrical along the obliqueplane where the second end of the spacer extends a distance beyond thefirst end of the spacer.
 5. The implant of claim 2, wherein the spacercomprises a leading taper asymmetrically positioned such that theleading taper crosses the oblique plane.
 6. The implant of claim 1,wherein the plate has an asymmetrical curved body.
 7. The implant ofclaim 1, wherein the implant is shaped and configured to allow for anoblique or anterolateral approach to the intervertebral space.
 8. Theimplant of claim 1, wherein the first and second ends of the plate andthe first and second ends of the spacer each comprise first and secondprojections with a recess defined therebetween, and wherein at least oneof the first and second projections of the plate or the spacer arematingly received in the corresponding recess of the plate or thespacer.
 9. The implant of claim 8, wherein the first projections of thespacer comprise a sloped upper surface which corresponds to a slopedlower surface of the first projections of the plate.
 10. The implant ofclaim 8, wherein the second projection of the plate is friction fitwithin the recess of the spacer.
 11. The implant of claim 1, wherein theat least one angled screw hole is configured to receive a fastener whichtraverses the anterior surface of the plate at an angle divergent to ahorizontal plane.
 12. The implant of claim 1, wherein the spacer and theplate define an open graft area extending from the superior surface tothe inferior surface of the spacer and configured to receive bone graftmaterial.
 13. The implant of claim 1, wherein the spacer includes aplurality of protrusions on the contact areas of the superior andinferior surfaces for engaging the adjacent vertebrae.
 14. The implantof claim 1 further comprising a locking mechanism disposed on the platefor preventing back out of at least one fastener from the at least onehole.
 15. The implant of claim 1, wherein the plate comprises abiocompatible metal.
 16. The implant of claim 1, wherein the spacercomprises a biocompatible plastic.
 17. An intervertebral implant forimplantation in an intervertebral space between adjacent vertebrae, theimplant comprising: a spacer having a superior surface, an inferiorsurface, a first end, and a second end, wherein the inferior surface andthe superior surfaces each have a contact area configured to engageadjacent vertebrae; a plate having an upper surface, a lower surface, afirst end, a second end, wherein the plate has an anterior surfacecomprising at least one eyebrow projecting past the upper or lowersurfaces and configured to provide passage for at least one angled screwhole; and a fastener for extending through the plate; wherein the plateis attached to the spacer in an assembled configuration such that thefirst end of the spacer engages the first end of the plate and thesecond end of the spacer engages the second end of the plate, andwherein when viewed from a top elevation, the implant is shaped suchthat no median plane divides the spacer and the plate in the assembledconfiguration into two symmetrical sections.